The invention relates to static seal structures. In particular, the invention relates to static seals for turbines, such as gas and steam turbines.
Seals are used between nozzle segments in turbines, engines, and other similar devices to prevent fluid flow between the segments. One known static seal assembly 101 for a nozzle segment is illustrated in FIG. 1. The seal assembly 101 comprises a metallic seal 100, which is an essentially flat, un-curved piece of metal. The metallic seal 100 defines generally flat, contact regions 104. The metallic seal 100 fits into grooves 102 in nozzle segments 103. The metallic seal 100 bridges a gap 105 formed by the grooves 102 and seals against the nozzle segments 103 at the contact regions 104. Thus, the seal assembly 101 reduces leakage at the grooves 102.
The above-described seal assembly 101 reduces leakage, however these seal assemblies depend on differential pressure to seal at the contact regions 104. The differential pressure is applied across the metallic seal 100 in direction 120 to force the contact regions 104 against the nozzle segments 103. The differential pressure maintains the contact regions 104 against the nozzle segments 103. The differential pressure against the metallic seal 100 may not always be sufficient for maintaining sealing pressure. Thus, these prior art seal assemblies may result in an inadequate seal.
Further, the differential pressure may vary due to operation of the turbine. Thus, the contact region 104 may not be forced with sufficient sealing pressure to be positioned and form a seal against the nozzle segments 103. The lack of sufficient sealing pressure is further apparent when the nozzle segments 103 move with respect to each other. The movement may result from one nozzle segment moving direction 103, regardless of the movement's cause. The generally flat, contact regions 104 do not move and may not remain in contact with the nozzle segments due to their flat configuration. Accordingly, the prior art metallic seal 100 may not exhibit an adequate seal against the nozzle segments 103.
Therefore, a static seal assembly that provides for enhanced sealing pressure is desirable. Additionally, a seal assembly that provides enhanced sealing pressure, regardless of differential pressure across it, is needed.